The use of lasers in medical applications has been increasing at a rapid pace particularly in the last decade. As in well known, lasers produce an intense beam of electromagnetic radiation of high spectral purity or monochromaticity which can be collimated to a fine degree with high radiation densities, small angular divergences and long coherent time. Such properties make lasers particularly attractive for a variety of medical uses.
For example, a process known as photo-coagulation has been developed primarily for medical procedures such as chorioretinal coagulation in which a laser beam is used to achieve fusion of the retina and choroid of the eye to overcome retinal detachments. As discussed for example in U.S. Pat. Nos. 3,720,213 to Hobart, et al; 3,703,176 to Vassiliadas, et al and 3,783,874 to Koester, et al, the process of photo-coagulation as applied to the retina and choroid consists of introducing a laser beam externally upon the cornea of the eye with the energy being directed in such a manner that it is concentrated at a selected point upon the fundus by refractive media of the eye so that tissues in a very localized area are congealed. The above cited patents disclose various devices for directing a laser beam to the appropriate external location on the cornea.
In contrast to laser energy, ultraviolet radiations may injure refractive media of the eye, and radiant energy may be dissipated or conducted into surrounding portions of the eye by the fundus making such forms of treatment unacceptable. The high intensity and small angular divergence of laser beams enables the desired amount of coagulation to occur in a short period of time, to a very confined area, with minimal excessive generation of heat.
In each of the patents discussed above and in virtually all photo-coagulation procedures, particularly chorioretinal coagulation, the laser beam is positioned externally of the eye at a predetermined, carefully defined location. A similar device is disclosed in U.S. Pat. No. 3,750,670 to Balanos, et al in which the repair of a retinal detachment or treatment of blood vessels of diabetics is taught using an apparatus described as a laser cauterizer. This apparatus is similar to the photo-coagulation devices discussed in the patents cited above and also involves external treatment of an affected area by laser energy.
Another medical use for laser energy is disclosed in U.S. Pat. No. 3,538,919 to Meyer. In this patent, a method of depilation by laser energy is taught in which a fiber optics rod covered by a catheter jacket acts as a conduit for delivery of a laser beam to a hollow needle mounted at one end of the fiber optics rod. The needle is inserted alongside a hair follicle and transmits a laser beam to the base of the follicle which is then destroyed by the heat intensity of the beam. Unlike the photo-coagulation use for a laser beam as discussed in the patents above, the Meyer method of depilation involves insertion of a needle or other laser beam transmitting conduit into the body. The high radiation density and small angular divergence property of the laser beam is used to advantage in Meyer wherein only that portion of the follicle in the immediate vicinity of the end of the needle is subjected to the laser energy and destroyed.
Areas of medical treatment in which the capability of laser energy has not been investigated include the intravascular treatment of blood vessels to create clotting, and the cosmetic treatment of unsightly blood vessels. It is therefore one object of this invention to provide an apparatus and method for creating, intravascularly, a blood clot within a vessel of a patient.
It is another object of this invention to provide an apparatus and method for creating scar tissue adjacent and overlapping a disfunctional blood vessel to cosmetically remove it from sight.